1. Technical Field
The present invention relates generally to digital signal processing and more particularly to relatively high-speed signal processing for various applications, such as communications.
2. Background Art
Signal processing may be described as the mathematical manipulation of signals in a predetermined manner to enhance, modify or otherwise alter the signal, typically to prepare the signal for additional post-processing applications. The input signals are often “sampled” data elements taken from various forms of analog signals such as voice, video, and various communication sources. After sampling, these analog signals may be processed by a variety of electronic systems to accomplish the desired results. Additionally, input signals may be originally presented as digital signals and many signal-processing environments provide signal processing capabilities for analog as well as digital signals.
Approximately 30 years ago, with certain advances in technology, digital signal processing applications started to proliferate. This momentum was fueled, in part, by the rapid growth of digital electronics, including the emergence of semiconductor-based transistors and microprocessors. Prior to the advent of relatively inexpensive digital signal processing hardware, signal processing was mostly accomplished with analog components, implemented as a series of filters such as high pass filters, low pass filters, band pass filters and the like. Presently, digital signal processing is used extensively in applications such as cellular telephones, video capture and enhancement, high-speed data modems and the like.
While many modem microprocessors used in typical digital signal processing applications today can handle data elements with a relatively large number of representative bits (e.g., 32, 64, and 128 bits), most of the sampled analog signals processed by these microprocessors have a much smaller representative data resolution (e.g., 4, 8 or 16 bits). This disparity in the size of the data representations results in wasted processor bandwidth and other processing inefficiencies. For example, if 8 bit data elements are loaded into 16-bit or 32-bit registers, the remaining register bits may remain unutilized. This inefficient use of available storage results in resource underutilization, which generally leads to increased signal processing times. In general, this inefficient processing can lead to “data-starvation” for the microprocessor, and the microprocessor consumes precious cycle time and energy waiting for data to arrive instead of processing data.
Accordingly, in an attempt to take advantage of the capabilities offered by the processors available in the industry today, various techniques such as “packed data types” have been implemented to improve data utilization in the field of digital signal processing. This involves storing multiple data elements in a single register. For example, a single 32-bit register might be loaded with four 8-bit data elements. This technique, while successfully utilizing the available storage space, requires relatively complex indexing algorithms to effect data retrieval and manipulation. Additionally, the data elements are often still retrieved from the 32-bit register as discrete 8-bit elements, requiring multiple machine cycles to retrieve the data for processing.
Alternatively and/or in addition to more efficient data storage techniques, some digital signal processing systems have increased the speed of the data bus in an attempt to provide the smaller data elements to the microprocessor at higher frequencies, thereby speeding the overall processor operations. However, even after implementing these various techniques, the microprocessors used in many digital signal-processing systems remain “data-starved ” and underutilized. This situation is undesirable because the lack of timely data presentation can, in certain circumstances, add additional processing cycles and, correspondingly, slow down the overall operation of the devices utilizing the processed signal.
Additionally, in the case of certain applications such as processing error correction codes and enabling and implementing encryption protocols for on-line data transfer, the manipulation of the data can be based on complex polynomial operations, leading to significant processing overhead. This type of data processing can consume precious processor cycles, thereby slowing down the overall response time of the system and delaying further processing until the data can be processes and formatted for use in the desired application. Since most data processors are not optimized for polynomial operations, the loss of processing power can be significant.
As shown by the discussion presented herein, the current constraints on data utilization in the area of digital signal processing have prevented additional improvements in the rapidly accelerating pace of various signal-processing applications. Accordingly, unless further improvements and enhancements are made in the apparatus and methods used in storing and manipulating data elements, the capabilities of digital signal processing systems will remain sub-optimal.